β-Elemene Inhibits Cell Proliferation by Regulating the Expression and Activity of Topoisomerases I and IIα in Human Hepatocarcinoma HepG-2 Cells

Abstract EN

Objective.

To investigate the effects of β-Elemene (β-ELE) on the proliferation, apoptosis, and topoisomerase I (TOPO I) and topoisomerase IIα (TOPO IIα) expression and activity of human hepatocarcinoma HepG-2 cells.

Methods.

After treatment with β-ELE, morphological alterations of HepG-2 cells were observed under an inverted microscope.

Cell proliferation was assessed using an MTT assay, cell cycles were analyzed using flow cytometry, and apoptosis was detected by Annexin V/PI staining.

The expression of TOPO I and TOPO IIα was analyzed by Western blot techniques, and their activity was measured using the TOPO I-mediated, supercoiled pBR322 DNA relaxation and TOPO IIα-mediated Kinetoplast DNA (kDNA) decatenation assays, respectively.

Supercoiled pBR322 and kDNA were also used to determine the direct effect of β-ELE on DNA breaks.

Results.

β-ELE significantly inhibited HepG-2 cell proliferation in a dose- and time-dependent manner.

β-ELE also induced tumor cell arrest at S phase, induced cell apoptosis, and downregulated the protein expression of TOPO I and TOPO IIα in a dose-dependent manner.

β-ELE also inhibited TOPO I- and TOPO IIα-mediated DNA relaxation but did not directly induce DNA breakage at any concentration.

Conclusion.

β-ELE could inhibit the proliferation of HepG-2 cells and interfere with the expression and activity of TOPO I and TOPO IIα.